Monday, November 8, 2010

Joint Probability of Being Mauled by a Bear and Struck by Lightning

This is an oldie but a goodie. A while ago, Ms. Sarah Bailey posted this article on my Facebook wall about a guy who got struck by lightning and mauled by a bear. They go on to say that the closest estimate of the probability of both of these things happening is zero. Agreed... for any random person.

Every person, of course, does not have the same probability of being hit by lightning and being mauled by a bear. Take Donald Trump, for example. While Zeus probably hates him for being the most pompous shit ever, thus making him about 1,000 times more likely to be hit by lightning than the normal person, I'd hazard a guess that he is rarely if ever within 100 miles of an un-caged bear.

On the other hand, look at Rick Oliver. According to the article, "he tends to piddle about his farm, checking on his chickens, working on his tractors and, as he was in the wee hours of June 3, fixing up his Chevy Malibu." It was while piddling that, upon hearing a mysterious noise off in the distance, he went alone to investigate. I'd say that sort of behavior makes you pretty darn likely to be mauled by a bear. It might also make you pretty darn likely to get struck by lightning if that same tendency to investigate noises outside also applies to thunder. 

Two points here: (1) these events are not independent. They are probably conditionally independent given a number of factors, such as rural-dwelling, gender==male, a love of Kenny Chesney, etc.  (2) If you meet several of those conditions (i.e. if you're the sort of person who goes looking for bears/lightning), as rare as occurrences of bear maulings and lightning strikes are in the overall population, I'd say you're fairly likely to be attacked by both.


  1. Kenney Chesney huh? You racist. Or rather, Ruralist!